UNIVEBSITY  OF  CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL   EXPERIMENT   STATION 

BERKELEY,   CALIFORNIA 


UTILIZATION  OF  WASTE  ORANGES 


BY 

W.  V.  CRUESS 


Orange  Culls 

BULLETIN  No.  244 

Berkeley,  Cal.,  March,  1914 


UNIVERSITY  OF  CALIFORNIA  PRESS 

BERKELEY 

1914 


Benjamin  Ide  Wheeler,  President  of  the  University. 

EXPERIMENT  STATION  STAFF 
HEADS   OF  DIVISIONS 

Thomas  Forsyth  Hunt,  Director. 

Eugene  W.  Hilgard,  Agricultural  Chemistry  (Emeritus). 

Edward  J.  Wickson,  Horticulture. 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;  Plant  Breeding. 

Hubert  E.  Van  Norman,  Vice-Director;  Dairy  Management. 

William  A.  Setchell,  Botany. 

Meyer  E.  Jaffa,  Nutrition. 

Robert  H.  Loughridge,  Soil  Chemistry  and  Physics  (Emeritus). 

Charles  W.  Woodworth,  Entomology. 

Ralph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Bernard  A.  Etcheverry,  Irrigation. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural  Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 

Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

James  T.  Barrett,  Plant  Pathology. 

Burr  B.  Pratt,  Pomology. 

William  G.  Hummel,  Agricultural  Education. 

Frank  L.  Peterson,  Farm  Mechanics. 

David  N.  Morgan,  Assistant  to  the  Director. 

Mrs.  D.  L.  Bunnell,  Librarian. 

DIVISION   OF  VITICULTURE   AND   ENOLOGY 

Frederic  T.  Bioletti  F.  C.  H.  Flossfeder 

L.  Bonnet  W.  F.  Oglesby 

W.  V.  Cruess  A.  E.  Way 


[156] 


UTILIZATION   OF  WASTE  ORANGES; 


BY 

W.  V.  CRUESS 


SUMMARY 

Orange  Juice. — A  very  palatable  and  attractive  beverage  can  be 
made  from  oranges.  The  chief  difficulty  is  the  mechanical  one  of 
rapidly  and  economically  separating  the  juice  from  the  solid  parts 
of  the  fruit.  The  juice  can  easily  be  made  perfectly  and  permanently 
clear  by  settling  and  nitration.  Sulfurous  acid  in  very  small  amounts 
is  necessary  to  prevent  fermentation  and  the  production  of  a  bitter 
taste  during  settling.  The  cleared  juice  keeps  perfectly  after  bottling 
if  pasteurized  at  180°  P.,  which  does  not  injure  the  flavor  perceptibly. 
Good  oranges  will  yield  over  130  gallons  per  ton.  Frozen  oranges 
less  than  half  of  this. 

Orange  Wine. — All  the  so-called  orange  wines  examined  were 
found  to  be  mixtures  and  decoctions  of  inferior  quality.  A  very 
agreeable  pure  orange  wine  can  be  made  by  the  use  of  proper 
methods.  These  methods  consist  of  defecation  with  sulfurous  acid, 
fermentation  with  pure  yeast  and  filtration.  This  wine  can  be  made 
sparkling  by  a  supplementary  fermentation  in  the  bottle. 

Orange  Vinegar. — From  orange  wine  a  fairly  good  vinegar  can 
be  made,  but  not  equal  to  wine  or  cider  vinegar.  Unless  careful  and 
appropriate  methods  are  used  the  vinegar  is  liable  to  be  below  legal 
strength. 


A  very  large  quantity  of  oranges  is  wasted  every  year  in  Cali- 
fornia. At  the  packing  houses,  any  orange  showing  a  defect  in  shape, 
color,  or  size,  or  a  slight  injury  to  the  skin  is  rejected.  The  total 
amount  wasted  in  this  way  is  variously  estimated  at  from  5  to  20 
per  cent  of  the  total  crop.  In  years  when  there  is  unusually  cold 
weather  it  may  be  much  greater. 

There  are  various  uses  to  which  rejected  oranges  could  be  put, 
and  a  small  number  of  them  are  now  used  in  the  manufacture  of 
various  citrus  by-products.  A  collection  of  such  by-products  was 
obtained  in  the  market  and  examined  at  the  Zymological  Laboratory. 


*  The  experiments  reported  in  this  publication  were  undertaken  at  the  sugges- 
tion of  Professor  F.  T.  Bioletti  and  the  methods  of  investigation  were  outlined 
by  him. 

[157] 


158  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

The  collection  consisted  of  various  preserves,  such  as  marmalades, 
dried  and  candied  peel,  bottled  pulps  and  syrups;  various  aliment- 
ary liquids  and  beverages  such  as  unfermented  orange  juice,  orange 
wine  and  orange  vinegar,  and  various  chemical  preparations,  such  as 
extracts,  essential  oils,  citric  acid  and  citrates.  Many  of  the  products 
were  of  good  to  fair  quality,  especially  those  which  can  be  prepared 
by  chemical  or  mechanical  means.  Others  were  bad,  especially  those 
the  preparation  of  which  involves  some  fermentation  process. 

Of  the  latter,  three  come  within  the  scope  of  the  work  of  the 
Zymological  Laboratory,  i.e.,  Orange  Juice,  Orange  Wine  and  Orange 
Vinegar.  Tests  already  made  at  the  laboratory  had  shown  that  it 
was  possible  by  simple  means  to  produce  and  preserve  a  very  attrac- 
tive, palatable  and  nutritious  juice  from  oranges.  A  further  series 
of  tests  was  undertaken  to  find  the  best  practical  methods  of  pre- 
paring this  juice,  and  further  to  see  whether  wine  and  vinegar  of 
commercial  value  could  also  be  produced  from  "cull"  oranges, 
especially  from  those  injured  by  frost. 

This  bulletin  gives  the  results  of  these  tests.  They  demonstrate 
that  it  is  possible  to  produce  not  only  an  orange  juice  that  will 
keep,  and  retain  the  agreeable  flavor  of  fresh  oranges,  but  also  a 
light,  refreshing  wine  with  pleasant  acidity  and  fresh  orange  flavor. 
A  fairly  good  vinegar  of  standard  strength  was  also  made,  but  not 
equal  in  quality  to  either  wine  or  cider  vinegar. 

The  chief  difficulty  in  the  way  of  manufacturing  any  of  these 
products  appears  to  be  the  mechanical  one  of  separating  the  juice 
cheaply  without  spoiling  it  by  mixing  with  the  juices  of  the  orange 
skin.  If  a  machine  could  be  devised  to  peel  the  orange  economically, 
the  remainder  of  the  process  would  be  simple. 

ORANGE  JUICE 

Yields  and   Composition. — A   number   of   tests   of   sound   and   of 

frozen  oranges  was  made  to  determine  the  volume   of  juice   which 

should  be  expected  from  a  ton  of  fruit.     The  yields  were  obtained  by 

crushing  the  pulp  from  weighed  lots  of  oranges  and  pressing  in   a 

small  meat  press. 

Table  1. — Yields  of  Juice 

Sample  Juice  per  cent  Juice  in  gals,  per  ton 

No.    715.     Frozen  Valencias  19.1  42.5 

No.    717.     Frozen  Navels  20.2  45.0 

No.  1110.     Sound  Valencias  55.3  132.8 

The  unfrozen  oranges  yielded  not  far  from  as  much  juice  as  can 
be  extracted  from  grapes;  the  frozen  oranges  only  about  25  to  30  per 
cent  as  much.    The  loss  of  juice  in  the  frozen  fruit  is  not  due  simply 


Bulletin  244]  UTILIZATION  OF  WASTE  ORANGES  159 

to  concentration  by  evaporation,  but,  at  least  in  great  part,  to  an 
actual  disappearance  of  the  juice  with  all  its  constituents  as  shown 
by  the  following  analyses: 

Table  2. — Composition  of  Juice 

Sample  Total  Solids  Total  Sugars  Acid  as  Citric 

1.  Juice  of  unfrozen  fruit,  1912-13 13.9%  11.3  1.42 

2.  Juice  of  frozen  fruit,  1912-13 16.2                       2.00 

3.  Juice  of  frozen  fruit,  1912-13 13.8  11.0  1.40 

4.  Juice  of  frozen  fruit,  1912-13 13.6                       1.30 

5.  Juice  of  unfrozen  fruit,  1912-13 13.0                       .90 

6.  Juice  of  unfrozen  fruit,  1912-13 12.0                       .99 

These  data,  showing  that  the  concentration  of  the  solids  in  the 
juice  from  the  frozen  and  unfrozen  oranges  is  about  the  same  and 
the  fact  that  there  is  a  much  greater  quantity  of  juice  in  the  unfrozen 
oranges,  indicate  a  disappearance  of  both  solids  and  liquid  after 
freezing. 

A  comparison  of  samples  1  and  2  might  indicate  a  slight  con- 
centration due  to  evaporation,  but  samples  1  and  3  show  practically 
the  same  composition.  On  the  whole,  the  composition  of  the  juice 
seems  to  be  little  affected  by  the  freezing  of  the  oranges. 

Orange  juice  according  to  these  analyses,  shows  nearly  three  times 
the  amount  of  acidity  found  in  grape  juice  and  five  or  six  times  the 
amount  found  in  apple  juice.  The  total  solids  are  about  two-thirds 
those  of  grape  juice  and  a  little  less  than  those  of  apple  juice. 

Clearing. — The  juice  should  be  made  permanently  bright,  so  that 
it  will  have  an  attractive  appearance  in  bottle.  Fresh  juice  will  not 
filter  easily  and  is  difficult  to  make  bright  by  filtration  until  it  has 
stood  a  certain  length  of  time.  The  length  of  time  necessary  varies 
considerably,  but,  in  all  the  tests  made  in  the  laboratory,  twenty-four 
to  seventy-two  hours  was  the  maximum  variation.  The  following 
observations  bring  out  the  effect  of  preliminary  defecation  by  stand- 
ing and  settling  on  the  clearing  of  the  juice  by  filtration. 

Table  3. — Effect  of  Standing  for  Various  Times  before  Filtering 

Sample  Observations 

1.  Fresh  juice  Filters  slowly  and  filtrate  is  cloudy. 

2.  Same  juice  after  18  hrs Filters  slowly  and  filtrate  is  cloudy. 

3.  Same  juice  after  52  hrs Filters  slowly  but  filtrate  is  clear. 

4.  Same  juice  after  76  hrs Filters  easily  and  filtrate  is  clear. 

Other  samples  of  juice  behaved  similarly,  except  that  in  most 
cases  the  time  necessary  for  defecation  was  less  than  the  seventy-six 
hours  noted  in  the  table.  One  sample  became  jelly-like  in  a  few 
hours  after  expressing  it  from  the  oranges,  but  two  days  later  the 


160  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

jelly-like  material  coagulated  and  settled  out,  carrying  down  all  sus- 
pended matter,  leaving  a  perfectly  bright  liquid  above.  Apparently 
a  coagulating  or  clotting  enzyme  is  active  in  bringing  about  the 
clearing  of  the  juice.  Further  evidence  for  the  existence  of  such  an 
enzyme  in  orange  juice  is  given  by  the  fact  that,  if  the  juice  is 
pasteurized,  it  will  not  clear,  but  will  remain  cloudy  until  filtered  or 
clarified  by  other  means.  It  is  a  property  of  all  enzymes  that  they 
are  destroyed  by  heat;  therefore  the  fact  that  unpasteurized  juice 
clears  of  its  own  accord  and  the  pasteurized  undefecated  juice  does 
not,  indicates  the  presence  of  such  an  enzyme. 

Several  samples  of  the  same  juice  were  treated  as  follows : 

1.  Defecated  50  hours  and  then  heated  in  bottles  to  185°  F. 

2.  Defecated  50  hours,  egg  albumen  added  at  the  rate  of  5  oz. 

per  100  gallons,  then  heated  in  bottle  to  185°  F. 

3.  Defecated  50  hours,  casein  added  at  the  rate  of  5  oz.  per  100 

gallons,  then  heated  in  bottle  to  185°  F. 

4.  Not  defecated ;  casein  added  at  rate  of  5  oz.  per  100  gallons 

immediately  after  pressing  and  then  heated  in  bottle  to 
185°  F. 

5.  Not  defecated;  heated  in  bottle  to  185°  F.  immediately  after 

extraction  from  the  fruit. 

Seven  months  later,  samples  1,  2  and  3  were  bright,  but  4  and  5 
were  cloudy.  These  tests  demonstrate  the  utility  of  defecation  in 
clearing  the  juice.  (Compare  especially  tests  3  and  4.)  They  also 
indicate  that  finings  are  unnecessary  for  the  clearing  of  the  juice. 
(Compare  test  1  with  tests  2  and  3.) 

Three  other  small  lots  of  juice  were  treated  in  the  following  ways : 

6.  Same  juice  as  No.  5,  defecated  seventy-six  hours  with  sul- 

furous  acid,  filtered,  pasteurized  at  185°  F.  in  bottle.    This 
juice  came  from  unfrozen  oranges. 

7.  Juice  from  frozen  oranges  tested  in  same  manner  as  No.  6. 

8.  Same  juice  as  No.  7.    Not  treated  with  sulfurous  acid.     Fil- 

tered several  times  till  bright   and  pasteurized  twice   at 

185°  F. 
Seven  months  after  pasteurization,  samples  6,  7,  8  were  all  bright. 
No.  6  was  of  a  slightly  lighter  shade  than  No.  7.  No.  8  was  dark 
brown  in  color.  Samples  6  and  7  exhibited  very  little  cooked  flavor; 
No.  8,  on  the  other  hand,  had  enough  of  the  cooked  taste  to  make  it 
considerably  inferior  to  samples  6  and  7.  Although  not  treated  with 
sulfurous  acid,  sample  8  did  not  have  a  very  pronounced  bitter  flavor, 
probably  because  it  was  sterilized  so  soon  after  extraction,  thus  not 
allowing  time  for  the  development  of  the  bitter  flavor. 


Bulletin  244]  UTILIZATION  OF  WASTE  ORANGES  161 

In  the  settling  out  process,  or  defecation  of  the  juice,  two  serious 
difficulties  are  met  with.  The  first  is  that  the  juice  will  start  to 
ferment  if  allowed  to  stand  long  enough  to  defecate,  unless  treated 
in  some  way  to  delay  fermentation.  Secondly,  a  bitter  taste  develops 
in  the  untreated  juice  if  it  is  long  exposed  to  the  air.  Tests  have 
shown  that  the  addition  of  moderate  amounts  of  sulfurous  acid  will 
prevent  fermentation  for  the  desired  length  of  time  and  will  also 
prevent  the  development  of  the  bitter  taste.  Since  sulfurous  acid 
acts  in  the  opposite  manner  to  the  oxygen  of  the  air,  it  may  be 
surmised  that  the  development  of  the  bitter  flavor  in  orange  juice 
is  due  to  the  oxidation  of  some  tasteless  constituent  of  the  juice  to  a 
bitter  form.  An  experiment  indicated  that  the  sulfurous  acid  must 
be  added  very  soon  after  the  oranges  are  crushed  in  order  to  check 
the  bitter  flavor,  as  in  this  particular  test,  a  bitter  taste  was  per- 
ceptible in  one-half  hour  after  the  juice  had  been  expressed.  The 
amount  of  sulfurous  acid  necessary  in  any  case  will  probably  not 
exceed  two  or  three  ounces  per  100  gallons  of  juice,  or  if  reckoned 
in  terms  of  the  form  in  which  it  is  most  usually  applied,  not  more  than 
four  to  six  ounces  of  potassium  metabisulfite.  The  latter  is  most 
conveniently  added  as  a  water  solution  which  is  made  up  so  that  each 
gallon  contains  the  amount  of  sulfite  necessary  for  200  gallons  of  the 
juice.  For  example,  if  it  is  desired  to  add  eight  ounces  to  each  200 
gallons,  a  solution  is  made  containing  eight  ounces  of  the  metabisulfite 
per  gallon  of  water. 

After  the  addition  of  the  potassium  metabisulfite,  the  juice  may 
be  allowed  to  stand  in  convenient  containers,  until  it  has  defecated 
long  enough  to  permit  rapid  filtration.  The  amount  of  sulfites  recom- 
mended are  well  below  the  limits  allowed  by  law  in  various  food 
products.  It  may  also  be  stated  that  a  great  deal  of  the  sulfurous 
acid  disappears  during  subsequent  treatment,  so  that  the  amount  left 
in  the  juice  is  negligible. 

Filtration. — After  the  juice  has  defecated  a  sufficient  length  of 
time,  it  may  be  filtered  without  difficulty  to  give  a  bright  liquid.  In 
this  process,  it  will  be  necessary  to  draw  off  the  clear  liquid  from  the 
sediment  in  the  defecating  vessel.  This  juice  can  undoubtedly  be 
filtered  in  a  commercial  way  in  any  of  the  good  filters  that  are  on  the 
market.  A  pulp  filter  would  probably  be  the  best  for  the  defecated 
juice.  The  sediment  from  the  defecating  vessel  may  be  thrown  on 
bag  filters  and  in  this  way  brightened;  it  cannot  be  passed  through 
the  pulp  filter  (because  of  clogging)  without  a  preliminary  filtering 
through  a  bag  filter. 


162 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


Orange  juice  is  much  more  easily  filtered  than  grape  or  apple  juice 
and  gives  on  filtration  a  very  brilliant  liquid.  This  juice  also  differs 
from  filtered  fresh  apple  or  grape  must  in  that  it  remains  bright  after 
heating;  fresh  grape  and  apple  juices  may  be  filtered  bright  but  will 
often  not  remain  bright  after  heating. 

Pasteurization. — The  juice  must  be  pasteurized  after  filtration  to 

prevent  fermentation.  It 
may  either  be  bottled  be- 
fore pasteurization  or  may 
be  pasteurized  and  stored 
in  barrels  until  it  is  con- 
venient to  bottle. 

If  the  juice  is  stored  in 
barrels  the  latter  must  be 
new  or  must  have  been  used 
only  for  juice  and  kept 
sterile  by  burning  sulfur 
tapes  in  them  when  empty. 
Before  filling,  the  bar- 
rels should  be  thoroughly 
steamed  to  sterilize  the  in- 
ner surface.  Several  forms 
of  pasteurizers  may  be  used 
in  the  heating  of  the  juice 
to  the  desired  temperature. 
One  of  the  simplest  types 
may  be  made  by  placing  a 
non-corrodable  metal  coil  in 
a  wooden  container  of  con- 
venient size.  Juice  may  be 
placed  in  this  container  and 
steam  passed  through  the 
coil.  The  coil  should  be 
kept  in  motion  during  the 
heating  in  order  to  avoid 
scorching  the  juice.  A  tin 
or  aluminum  coil  will  not  be  attacked  by  the  orange  juice.  Double 
jacketed  aluminum  kettles  are  used  with  success  in  the  pasteurization 
of  grape  juice  and  apple  cider,  and  would  no  doubt  give  satisfaction 
in  the  sterilization  of  orange  juice.  Steam  is  passed  between  the  walls 
of  the  kettle  to  heat  the  juice. 


Discontinuous  Pasteurizer 


Bulletin  244]  UTILIZATION  OF  WASTE  ORANGES  163 

Both  of  the  above  heaters  are  discontinuous  in  their  action.  "Where 
a  continuous  flow  of  sterilized  juice  is  desired,  a  continuous  pasteurizer 
may  be  constructed  by  placing  a  tin  pipe  inside  of  an  iron  pipe.  Steam 
may  be  passed  through  the  outer  pipe  and  juice  through  the  inner  tin 
pipe.  By  varying  the  steam  pressure  and  the  flow  of  juice,  the 
desired  temperature  may  be  attained.  Continuous  pasteurizers  suit- 
able for  this  purpose  are  obtainable. 

In  any  case,  the  juice  should  reach  a  temperature  of  185°  F.  It 
should  then  be  run  into  clean  barrels.  The  barrels  should  be  bunged 
immediately  with  a  new  bung  covered  with  a  clean  cloth.  The  barrel 
should  then  be  rolled  on  its  side  to  sterilize  the  bung  with  the  hot 
juice.  The  flavor  of  orange  juice  seems  less  easily  injured  by  over- 
heating than  that  of  grape  or  apple  juice. 

During  the  first  few  weeks  of  storage,  the  barrels  must  be  carefully 
watched  in  order  that  those  which  start  to  ferment  may  be  detected 
in  time  to  save  them.    With  careful  work  few,  if  any,  should  ferment. 

Pasteurization  in  Bottles. — Whether  the  juice  is  bottled  immedi- 
ately after  filtering  or  stored  first,  for  a  time,  in  barrels,  it  must 
receive  a  final  pasteurization  after  bottling.  The  bottles. and  corks 
and  caps  that  are  used  must  be  clean.  Capping  is  preferable  to 
corking,  because  it  gives  less  trouble  in  handling  and  gives  a  neater 
appearance  to  the  bottle.  There  are  two  types  of  caps,  the  Crown 
cap  and  the  Goldy  cap  or  stopper.  The  Crown  cap  is  the  ordinary 
beer  bottle  or  soda  water  bottle  cap,  while  the  Goldy  stopper  is  the 
aluminum  cap  seen  on  grape  juice  and  pineapple  juice  bottles.  The 
latter  type  is  more  expensive,  but  is  preferable.  The  bottles  must  be 
sterilized  immediately  after  filling  and  capping.  A  convenient  form 
of  pasteurizer  may  be  used  by  placing  a  false  bottom  in  a  rectangular 
wooden  tank.  Under  the  false  bottom  is  placed  a  steam  coil.  The 
bottles  are  placed  on  the  false  bottom,  water  is  admitted  so  that  its 
level  is  about  three-fourths  the  height  of  the  bottles.  The  pasteurizer 
must  be  covered  in  order  that  the  caps  and  tops  of  the  bottles  will  be 
heated  by  the  escaping  steam.  One  bottle  may  be  left  uncapped. 
A  thermometer  is  placed  in  this  bottle  and  the  rise  in  temperature 
noted.     The  liquid  in  the  bottles  must  reach  a  temperature  of  180°  F. 

The  bottles  may  then  be  removed  and  allowed  to  cool.  They  should 
be  stored  until  it  is  seen  whether  the  pasteurization  has  been  successful 
and  whether  any  of  the  bottles  develop  cloudiness.  Three  weeks  or 
a  month  will  probably  be  sufficient  in  most  cases.  If  the  juice  remains 
clear,  it  may  be  put  on  the  market.  In  laboratory  tests  the  juice 
pasteurized  in  bottles  developed  a  slight  sediment  after  three  months, 
but  so  small  in  volume  as  to  be  scarcely  noticeable. 


164  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

To  some,  the  imclarified  juice  might  be  preferable  to  the  clear. 
If  such  a  juice  is  to  be  produced,  no  filtration  is  necessary  and  the 
juice  can  be  placed  in  bottles  imediately  and  sterilized.  Its  appear- 
ance would  probably  not  be  pleasing,  hence  would  have  to  be  disguised 
in  dark  bottles. 

Summary. — It  is  recommended  that  the  freshly  expressed  juice  be 
allowed  to  defecate  until  it  becomes  fairly  clear.  To  prevent  fermen- 
tation during  this  period  and  to  check  the  development  of  a  bitter 
flavor,  a  moderate  amount  of  sulfurous  acid  should  be  added  to  the 
juice,  immediately  after  crushing.  Potassium  metabisulfite  is  a  con- 
venient form  in  which  to  add  the  sulfurous  acid.  The  defecated 
juice  should  be  filtered.  It  may  then  be  bottled  immediately  and 
pasteurized,  or  may  be  pasteurized  in  barrels  and  kept  until  it  is 
desired  to  bottle  it.  The  bottled  juice  should  be  sterilized  at  180  to 
185  degrees  Fahrenheit  to  prevent  fermentation  and  mold  growth, 
especially  the  latter. 

ORANGE  VINEGAR 
The  samples  or  orange  juice  thus  far  examined  have  averaged  by 
chemical  test  about  11  per  cent  actual  total  sugars.  This  would  on 
fermentation  give  about  5.5  per  cent  alcohol  if  the  fermentation  were 
carefully  conducted.  Theoretically,  1  per  cent  of  alcohol  will,  after 
conversion  into  acetic  acid,  give  1.2  per  cent  acetic  acid.  Actually, 
1  per  cent  of  alcohol  gives  approximately  1  per  cent  of  acetic  acid. 
Therefore  orange  juice  of  the  above  composition  should  give  vinegar 
containing  considerably  over  the  minimum  legal  limit  of  4  per  cent 
acetic  acid. 

Table  4. — Variation  in  Composition  of  Orange  Juice 

Balling 
Sample  Total  Solids  Total  Acid  Sugar 

Frozen  Valencias,  Riverside,  1912-13  12.2  1.5 

Frozen  Valencias,  Riverside,  1912-13  13.8  1.4                  11.0 

Frozen  Navels,  Riverside,  1912-13  16.1  2.2 

Unfrozen  Navels,  Los  Angeles,  1912-13  13.0  .90 

Unfrozen  Navels,  Los  Angeles,  1912-13  13.9  1.42                11.3 

Unfrozen  Valencias,  Tulare,  1913-14  13.5  1.5  

Unfrozen  Navels,  Tulare,  1913-14  11.5  1.3 

Unfrozen  Navels,  Redlands,  1913-14  12.1  .9 

Crushing,  Pressing  and  Defecation. — The  juice  may  be  extracted  in 
the  same  way  as  in  the  production  of  unfermented  orange  juice.  For 
the  same  reasons  as  in  the  case  of  the  unfermented  juice,  the  juice  to 
be  used  for  vinegar  should  be  treated  with  potassium  metabisulfite 
and  allowed  to  defecate  before  fermentation.     Four  to  six  ounces  of 


Bulletin  244]  UTILIZATION  OF  WASTE  ORANGES  165 

the  sulfite  dissolved  in  water  will  be  sufficient  for  each  100  gallons 
of  juice.  The  clear  juice  may  be  drawn  off  after  defecation  and  the 
mud  may  be  filtered  through  bag  filters.  It  is  necessary  to  remove  all 
of  the  pulp  because  it  will  rise  during  yeast  fermentation  and  form 
a  cap  on  which  mold  growth  is  very  apt  to  take  place ;  furthermore 
the  pulp  may  give  trouble  in  the  acetic  acid  fermentation  that  follows 
the  alcoholic  fermentation. 

Alcoholic  Fermentation. — The  production  of  vinegar  from  any 
sugary  liquid  depends  on  two  separate  and  distinct  fermentations.  The 
first  of  these  consists  in  the  transformation  of  the  sugar  into  alcohol 
and  carbon  dioxide  and  is  brought  about  by  the  activity  of  yeasts.  The 
second  is  the  change  of  the  alcohol  into  acetic  acid.  This  latter  change 
is  carried  on  by  vinegar  bacteria.  For  the  successful  production  of 
vinegar,  conditions  should  be  favorable  to  the  activity  of  a  desirable 
type  of  yeast  during  the  alcoholic  fermentation  and  unfavorable  to  all 
other  classes  of  yeasts.  During  the  acetic  fermentation  the  activities 
of  the  vinegar  bacteria  should  be  favored  as  much  as  possible. 

Orange  juice  left  to  itself  develops  many  different  types  of  yeasts 
and  molds,  and  undergoes  a  fermentation  that  results  in  a  low  yield 
of  alcohol  and  a  fermented  juice  of  poor  flavor.  Hence  it  is  desirable 
to  add  pure  yeast  to  the  defecated  juice  in  order  that  a  good  fermenta- 
tion will  result.  Such  a  yeast  is  distributed  from  the  Enology  Labor- 
atory of  the  University  and  may  be  had  on  application.  Full  directions 
for  its  use  and  propagation  are  sent  with  the  yeast. 

If  grown  in  well  defecated  and  sulfited  juice,  the  yeast  will  remain 
sufficiently  pure,  throughout  the  season,  if  used  according  to  directions 
accompanying  the  sample  sent  from  the  Enology  Laboratory.  The 
following  figures  were  obtained  in  laboratory  fermentations  of  orange 
juice. 

Table  5. — Yields  of  Alcohol  from  Orange  Juice 


Sample 

Balling 
of  Juice 

Possible 
Alcohol 

Alcohol 
obtained 

Loss  due  to 
Natural  Yeast 

1.  Pure  Yeast  fermentation 

11.2% 

4.25% 

4.25% 

2.  Natural  fermentation  .... 

12.8 

5.18 

4.5 

.68% 

Sample  No.  1  was  fermented  with  pure  yeast;  No.  2  was  allowed 
to  ferment  naturally.  Although  the  Balling  was  1.6%  higher  in  the 
latter  case,  the  yield  of  alcohol  was  only  .3%  higher,  indicating  a 
greater  efficiency  in  the  pure  yeast  fermentation.  It  may  be  stated 
that  the  natural  fermentation  in  No.  2  was  carried  on  largely  by  un- 
desirable types  of  yeast.  This  also  happened  in  most  cases  where  the 
juice  was  allowed  to  ferment  spontaneously.  In  Sample  No.  2,  a  heavy 
growth  of  film  forming  yeast  developed,  giving  a  disagreeable  flavor 


166  UNIVERSITY  OF   CALIFORNIA EXPERIMENT   STATION 

as  well  as  causing  the  liquid  to  clear  very  slowly  after  fermentation. 
On  the  other  hand,  the  juice  fermented  with  the  pure  yeast  had  a 
clean  flavor  and  was  easily  cleared. 

Vinegar  Fermentation. — The  transformation  of  the  alcohol  of  the 
fermented  orange  juice  into  acetic  acid  takes  place  only  with  an 
abundant  supply  of  air  because  it  consists  in  the  addition  of  the  oxygen 
of  the  air  to  the  alcohol,  in  this  way  changing  it  into  acetic  acid  or 
vinegar.  However,  if  one  should  attempt  to  make  vinegar  by  simply 
exposing  freshly  fermented  orange  juice  to  the  air,  vinegar  fermenta- 
tion would  not  ensue.  In  its  place,  there  would  be  a  vigorous  growth 
of  wine  flowers  which  would  destroy  the  alcohol  without  the  forma- 
tion of  acetic  acid.  Therefore  something  must  be  done  to  encourage 
the  growth  of  the  vinegar  bacteria  and  discourage  the  development  of 
the  wine  flowers.  By  adding  a  considerable  amount  of  strong  vinegar 
to  the  orange  wine,  the  per  cent  of  acetic  acid  is  raised  sufficiently  to 
give  the  vinegar  bacteria  a  good  advantage  over  the  wine  flowers.  The 
addition  of  vinegar  also  inoculates  the  liquid  with  a  large  number  of 
vinegar  bacteria  and  will  give  a  rapid  start  to  the  vinegar  fermenta- 
tion. The  first  lot  of  vinegar  could  be  started  in  this  way  with  strong 
cider  or  wine  vinegar  free  from  vinegar  eels;  vinegar  equal  to  about 
one-fourth  of  the  volume  of  the  liquid  to  be  acetified  should  be  added 
to  the  fermented  juice.  When  this  has  been  changed  to  vinegar,  three 
fourths  of  the  vinegar  may  be  drawn  off  and  replaced  with  new  alco- 
holic liquid.  The  one-fourth  left  from  the  previous  lot  serves  to  start 
the  next  vinegar  fermentation  and  prevents  the  growth  of  wine 
flowers. 

A  convenient  form  of  vinegar  barrel  may  be  made  by  filling  an 
ordinary  fifty  gallon  barrel  about  three-fourths  full  of  fermented  juice 
and  then  boring  a  hole  in  each  end  a  few  inches  above  the  level  of  the 
liquid.  The  holes  must  be  covered  with  several  layers  of  mosquito 
netting  or  a  heavily  tin  plated  wire  gauze  to  prevent  the  access  of  vine- 
gar flies.  Bulletin  227  of  the  University  of  California  Experiment 
Station  gives  a  description  and  drawing  of  the  construction  of  such  a 
barrel.  On  a  large  scale,  a  vinegar  generator  could  probably  be  used, 
though  it  is  problematical  whether  a  generator  would  give  a  vinegar  of 
sufficiently  high  acid  content  because  of  the  greater  waste  of  alcohol 
in  the  generators  as  compared  to  the  slow  process.  The  construction 
of  a  vinegar  generator  is  described  in  Bulletin  227. 

The  progress  of  the  vinegar  fermentation  should  be  followed  by 
the  use  of  a  Leo  or  a  Twitchell  acetometer  so  that  the  point  at  which 
the  vinegar  fermentation  is  complete  may  be  noted.  This  will  be  when 
there  is  no  further  increase  in  the  acidity  of  the  vinegar.     The  use  of 


Bulletin  244]  UTILIZATION  OF  WASTE  ORANGES  167 

the  acetometer  is  explained  in  Bulletin  227,  which  may  be  had  on 
application  to  the  Director,  Agricultural  Experiment  Station, 
Berkeley. 

Table  6  gives  the  results  obtained  at  the  laboratory  from  three 
samples  of  orange  juice  by  following  the  method  described  above. 
Another  sample  was  fermented  and  allowed  to  stand  on  the  pulp  to 
note  whether  vinegar  fermentation  took  place.  This  material  was 
attacked  by  green  mold  and  finally  by  putrefactive  bacteria.  The 
juice  turned  to  an  evil  smelling  liquid  devoid  of  acid   or   alcohol. 

Another  large  sample  was  fermented  carefully  and  drawn  off  the 
yeast  sediment.  It  was  then  allowed  to  stand  exposed  to  the  air. 
Vinegar  fermentation  did  not  ensue  but  the  juice  became  covered 
with  a  heavy  growth  of  wine  flowers.  It  finally  became  very  flat 
tasting  and  totally  unfit  for  vinegar  making. 

The  results  obtained  from  the  juice  made  into  vinegar  by  yeast 
fermentation  followed  by  vinegar  fermentation  brought  about  by  the 
addition  of  strong  vinegar  equal  in  volume  to  one-fourth  the  volume 
of  the  fermented  juice,  are  given  in  the  following  table : 

Table  6. — Yields  of  Acetic  Acid  in  Orange  Vinegar  erom  Frozen  Oranges 


Sample 
1.    717d 

Balling  per  cent 

of 
Original  Juice 

12.2 

Total  Acid 

in 

Vinegar 

6.44 

Volatile  Acid 

(Vinegar  Acid) 

in  Vinegar 

5.18 

Alcohol 

in 
Vinegar 

Trace 

2.  717e 

12.5 

4.36 

3.36 

Trace 

3.   73  If 

12.5 

4.80 

3.60 

Trace 

The  juice  for  sample  1  was  defecated  with  the  help  of  sulfurous 
acid  and  the  clear  juice  was  fermented  with  pure  yeast.  The  clear  wine 
was  allowed  to  stand  several  days  after  alcoholic  fermentation  and 
was  then  drawn  off  the  yeast  and  fermented  into  vinegar  by  use  of  a 
vinegar  starter.  The  juice  for  samples  2  and  3  was  made  from  the 
same  oranges  as  that  of  sample  1.  This  juice  was  divided  into  two 
equal  portions.  Neither  received  any  sulfurous  acid  or  defecation  and 
both  were  fermented  with  pure  yeast.  The  wine  of  sample  2  was  drawn 
off  the  yeast  and  acetic  fermentation  carried  out  as  in  sample  1. 
Sample  3  was  treated  in  the  same  manner  as  sample  2  except  that  the 
wine  was  not  drawn  off  the  yeast  and  sediment  before  acetic  fer- 
mentation. 

The  use  of  sulfurous  acid  and  defecation  seemed  to  favor  a  better 
vinegar  fermentation,  or  at  least  resulted  in  a  higher  yield  of  acetic 
acid  than  where  no  sulfurous  acid  or  defecation  was  used.  The 
presence  of  the  yeast  and  sediment  during  acetic  fermentation  ap- 
parently had  little  or  no  effect  on  the  yield  of  acetic  acid  where  a 
vinegar  starter  was  used.     It  is  probable,  however,  that  the  sediment 


168  UNIVERSITY  OF   CALIFORNIA EXPERIMENT   STATION 

would  injure  the  flavor  if  left  during  acetic  fermentation  and  should 
therefore  be  removed  by  drawing  the  wine  from  it. 

The  acetic  acid  in  sample  1  was  well  above  the  legal  pure  food 
standard  of  four  per  cent  while  samples  2  and  3  were  below  this  stand- 
ard. If  the  total  acid,  instead  of  acetic  acid,  is  taken  as  the  measure 
of  the  strength  of  the  vinegar,  then  all  three  samples  satisfy  the  pure 
food  requirements.  Commercially,  a  vinegar  of  4%  total  acid  is  called 
a  "40  grain"  vinegar  which  is  the  legal  standard. 

Most  of  the  orange  flavor  was  lost  during  vinegar  fermentation  and 
the  flavor  of  the  finished  vinegars  was  not  so  agreeable  as  that  of 
apple  or  wine  vinegar.  The  inclusion  of  a  little  of  the  orange  oil 
from  the  skins  during  extraction  of  the  juice  might  improve  the  flavor, 
or  at  least  increase  the  orange  flavor. 

Clearing  the  Vinegar. — All  of  the  vinegar  samples  made  in  the 
laboratory  were  easily  filtered  bright.  The  addition  of  a  small  amount 
of  infusorial  earth  to  the  first  vinegar  which  was  passed  through  the 
filter  aided  a  great  deal  in  giving  a  clear  filtrate.  For  the  filtration 
of  the  vinegar  on  a  commercial  scale,  a  pulp  filter  could  be  used. 
Such  a  filter  would  have  to  be  heavily  tinned  to  prevent  solvent 
action  of  the  vinegar  on  the  metal  parts  of  the  filter. 

Wine  and  cider  vinegar  may  be  clarified  by  the  addition  of 
isinglass  dissolved  in  a  small  amount  of  the  vinegar.  There  is  little 
doubt  that  orange  vinegar  would  yield  to  the  same  treatment,  although 
tests  were  not  made  on  this  point. 

Summary. — Orange  vinegar  may  be  made  if  the  following  points 
are  observed.  The  fresh  juice  should  be  treated  with  four  to  six  ounces 
of  potassium  metabisulfite  per  100  gallons  of  juice  and  the  juice 
allowed  to  stand  and  deposit  its  gross  sediment  for  twenty-four  hours 
or  more.  The  clear  juice  should  be  drawn  off  and  fermented  with 
pure  yeast.  Immediately  after  alcoholic  fermentation  the  fermented 
juice  should  be  drawn  off  the  yeast  and  stored  in  well-filled,  closed 
barrels  or  tanks  until  it  is  convenient  to  turn  the  juice  into  vinegar. 
Strong  vinegar  equal  in  amount  to  about  one-fourth  the  volume  of 
the  fermented  juice  should  be  added  to  the  orange  wine  to  prevent 
the  growth  of  wTine  flowers  and  promote  the  development  of  the 
vinegar  fermentation.  The  vinegar  fermentation  must  take  place  in 
containers  that  allow  a  good  surface  of  the  vinegar  to  be  exposed  to 
the  air.     The  vinegar  may  be  cleared  by  filtering. 

OEANGE  WINE 
Beverages  are  met  with  at  present  bearing  the  name  of  orange 
wines.     All  samples  so  far  examined  at  the  laboratory  have  proved 
to  be  sweet  liquors  with  medium  to  high  alcoholic  content  and  with  a 


Bulletin  244]  UTILIZATION  OF  WASTE  ORANGES  169 

flavor  of  orange  extract  or  orange  oil.  They  gave  evidence  of  having 
been  made  from  sherry,  sweetened  by  the  addition  of  sugar  and 
flavored  by  the  addition  of  orange  extract  or  oil  in  some  cases,  and 
in  others  of  having  been  made  from  poorly  fermented  orange  juice 
fortified  by  the  addition  of  alcohol  and  sweetened  by  large  additions 
of  sugar.    Analyses  of  such  ' '  wines ' '  are  given  in  the  following  table  : 

Table  7. — Analyses  of  "Orange  Wines" 

Sample  Alcohol  Total  Acid  Volatile  Acid  Total  Sugar 

1  9.6%  .47%  m  21.6% 

2  9.6  .26  18.9 

3  18.0  .08  17.6 

Sample  3  was  evidently  a  sherry  flavored  with  orange  oil  or  extract 
and  sweetened.  Numbers  1  and  2  may  have  been  partially  fermented 
orange  juice  that  had  started  to  turn  to  vinegar  and  had  been  then 
fortified  by  the  addition  of  alcohol  or  brandy  and  sweetened  by  the 
addition  of  sugar  or  syrup.  These  are  all  "liqueurs"  of  bad  quality 
and  mis-labeled,  as  their  composition  and  flavor  show  that  they  have 
no  right  to  the  title  "Orange  Wine. 


?  i 


Table  8. — Analyses  of  Orange  Wines  Made  in  the  Laboratory 

Sample  Alcohol  Total  Acid 

1  4.25%  1.5% 

2  4.5  1.52 

Neither  of  these  wines  gave  any  perceptible  taste  of  sugar.  Both 
were  very  low  in  alcohol  as  compared  with  the  artificial  orange 
liqueurs  cited  in  Table  5.  The  acid  in  the  true  orange  wines  is  very 
much  higher  than  that  in  the  artificial  product.  Some  of  the  wines* 
were  made  in  the  laboratory  by  treating  the  fresh  juice  with  potassium 
metabisulfite  at  the  rate  of  four  to  six  ounces  per  100  gallons  and 
allowing  the  juice  to  settle  until  clear.  Pure  yeast  was  added  to  the 
clear  juice  after  drawing  it  off  the  sediment.  Another  lot  of  the  juice 
was  allowed  to  ferment  naturally.  Both  lots  of  wine  were  filtered 
after  fermentation.  Neither  gave  any  trouble  in  filtering  and  both 
gave  a  brilliantly  clear  wine. 

Most  of  the  juice  was  pasteurized  at  150°  F.  after  fermentation 

and  filtration  into  small  bottles.     The  pasteurization  did  not  affect 

the  brightness  of  the  wines,  but  did  give  a  little  cooked  flavor  to  the 

sample  that  was  not  treated  with  potassium  metabisulfite.    The  sulfited 

wine  did  not  develop  the  cooked  flavor  to  any   appreciable  extent. 

The  flavor  of  the  wine  made  by  the  use  of  defecation  and  pure  yeast 

was  superior  to  that  of  the  wine  made  by  natural  fermentation.     The 

*  For  a  fuller  account  of  the  methods  of  wine-making,  see  Bulletin  213,  ''The 
Principles  of  Wine-making,"  a  copy  of  which  can  be  obtained  on  request  from 
the  Agricultural  Experiment  Station  at  Berkeley. 


170  UNIVERSITY  OF   CALIFORNIA EXPERIMENT   STATION 

naturally  fermented  wine  was  of  a  little  darker  eolor  than  the  wine 
made  with  the  sulfurous  acid  and  pure  yeast. 

A  small  sample  of  the  fermented  juice  was  left  unpasteurized  in 
a  well-filled,  tightly  corked  bottle  at  the  prevailing  room  temperature 
of  22°  C.  (or  72°  F.).  After  three  months'  storage,  it  was  still  in 
the  same  condition  in  which  it  was  placed  in  the  bottle,  indicating 
that  the  wine  may  be  kept  without  pasteurization,  provided  it  is 
stored  in  well-filled  packages.  Two  samples  of  the  unpasteurized 
wine  left  in  partially  filled  bottles  developed  penicillum  mold.  Where 
it  is  to  be  subjected  to  high  temperatures,  it  should  be  pasteurized, 
because  it  does  not  contain  sufficient  alcohol  to  protect  it  against 
spoiling  by  bacterial  fermentation.  A  pasteurization  temperature  of 
140°  to  150°  F.  would  probably  be  sufficient. 

Sparkling  Wines. — The  filtered  wine  may  be  made  into  sparkling 
wine  as  follows,  after  the  first  fermentation  is  over.  To  the  filtered 
wine  1.5  per  cent  cane  sugar  previously  made  into  a  thick  syrup  and 
boiled  with  a  little  citric  acid  should  be  added  to  the  wine.  This  would 
be  about  1.8  ounces  of  sugar  per  gallon  of  wine.  To  this,  a  little 
champagne  yeast  may  be  added  and  the  wine  bottled  in  champagne 
bottles.  The  bottles  should  be  corked  with  champagne  corks  and  left 
in  a  warm  place  for  a  few  days  until  fermentation  starts  in  the 
bottles.  The  corks  must  fit  very  tightly  and  must  be  well  tied  down. 
During  the  first  few  weeks,  the  bottles  should  be  turned  often  to 
prevent  the  yeast  from  sticking  to  the  sides  of  the  bottles.  They  may 
then  be  placed  in  a  cool  place  until  fermentation  in  the  bottle  is 
complete.  They  should  then  be  placed  with  the  cork  downward  for 
several  months.  The  yeast  sediment  will  settle  out  on  the  cork.  The 
bottle  may  then  be  held  at  a  slanting  position  and  the  cork  released 
by  cutting  the  string  that  holds  it.  It  will  then  be  shot  out  of  the 
bottle  by  the  gas  pressure  in  the  bottle  and  carry  the  yeast  sediment 
with  it.  The  cork  must  then  be  replaced  by  a  new  cork,  immediately, 
before  the  gas  escapes  or  before  too  much  of  the  wine  is  lost  by  the 
escape  of  the  gas. 

A  sparkling  orange  wine  made  in  the  laboratory,  but  not  relieved 
of  its  yeast  sediment  as  described  above,  made  a  pleasing  drink.  It 
was  preferable  to  the  still  wine  made  from  the  same  juice. 

Summary. — Orange  wine  may  be  made  by  defecating  the  fresh  juice 
after  the  addition  of  moderate  amounts  of  potassium  metabisulfite  to 
prevent  fermentation  for  a  short  time,  fermenting  the  clear  juice  with 
pure  yeast,  and  filtering  the  finished  wine  to  clear  it.  This  cleared 
wine  may  be  turned  into  sparkling  orange  wine  by  the  addition  of  a 
small  amount  of  sugar  and  by  subsequent  fermentation  in  bottles. 


